Cyclic six-membered palladium complexes derived from palladium mediated C–N coupling of organonitrile and formamidine

Abstract

Reactions of N,N′-bis(2,6-diisopropylphenyl)formamidinium chloride (1) with palladium acetate in acetonitrile or propanenitrile results in the formation of cyclic six-membered triazapentadiene-palladium dichloride complexes (4 and 5). The reaction of formamidinium salt containing non-coordinating anions, such as (BF₄)⁻ (2) and (PF₆)⁻ (3) with palladium acetate in acetonitrile or propanenitrile leads to the formation of cationic bis(1,3,5-triazapentadiene)palladium complexes 6, 7 or 8, 9 respectively. However, the reaction with acrylonitrile afforded an unprecedented cyclic and anionic six-membered palladacycle complex (10). In addition a reaction of 1 with Pd(OAc)₂ in THF afforded an acyclic palladium complex (11), which is a possible intermediate formed before conversion to the cyclic six-membered palladium complexes (4, 5 and 10) in presence of organonitriles.